Method of producing 6-substituted (s)-Nicotine derivatives and intermediate compounds

ABSTRACT

A method of producing a 6-substituted (S)-nicotine derivative with the general formula (III), wherein R is an optionally substituted alkyl, alkenyl, alkynyl, amido or amino group, optionally coupled to a carrier protein, is disclosed. An intermediate compound useful in the method is also comprised by the invention. The formula of the compound is (A) in which A represents the cationic radical of an organic nitrogen base, Y represents an anion formed by an electrophilic compound.

[0001] The present invention relates to a method of producingenantiomerically pure 6-substituted (S)-nicotine derivatives and to newintermediate compounds for use in said method.

BACKGROUND OF THE INVENTION

[0002] There are several patent applications and published articlesdirected to vaccines/immunogens against nicotine dependency/harmreduction, but no such vaccines/immunogens are yet on the market.

[0003] One approach is directed to a vaccine/immunogen that in anindividual can elicit antibodies which strongly bind toadministered/inhaled nicotine and block its effect before it reaches thecentral nervous system. The desired result is that the individual willnot experience the expected stimulating effect of nicotineadministration/smoking, and therefore the interest in administering atobacco product, such as moist snuff, or lighting a cigarette will cease(extinction/prevention).

[0004] A complementary approach is directed to an immunogen that in anindividual can elicit antibodies which moderately or weakly bind toadministered/inhaled nicotine and enhance/prolong its effect in thecentral nervous system. The desired result is that the individual willexperience the expected stimulating effect of nicotineadministration/smoking during a prolonged period of time, and thereforethe interest in a renewed administration of a tobacco product, such asmoist snuff, or lighting a cigarette will be postponed and the medicalconsequences of the tobacco product consumption will be reduced.

[0005] Both of the above mentioned approaches use immunogens which in anindividual induces an immunological response which leads to harmreduction.

[0006] Papers disclosing active immunization to alter nicotinedistribution was recently published (Hieda Y. et al, J. Pharmacol. Exp.Therap. 1997, 283, 1076-1081, Pentel, P. R. et al, Pharmacol. Biochem.Behav. 2000, 65, 191-198). The immunogens used in the Hieda and Pentelarticles were (±)-6-(carboxymethyl-ureido)-nicotine conjugated tokeyhole limpet hemocyanin and (±)-trans-3′-aminomethylnicotineconjugated to Pseudomonas aerigunosa exoprotein A via a succinic acidlinker, respectively.

[0007] The international patent application WO 98/14216 claims a largenumber of hapten-carrier conjugates based on the nicotine molecule andthe common structural feature of the compounds seems to be that all ofthe hapten molecules contain a terminal carboxylic acid group which isthen conjugated to the carrier. No in vivo testing has been disclosedfor the alleged drug abuse treatment.

[0008] Other nicotine derivatives useful in vaccines/immunogens arecomprised by the present inventors' International patent applicationWO9961054A1 directed to nicotine immunogens comprising 5- or6-nicotinyl-linker-carrier proteins.

[0009] All the published 6-nicotine derivatives are produced asracemates, and if an enantiomer is desired, the production isaccomplished by procedures for separating racemic mixtures intooptically pure fractions well known in the art (see for example U.S.Pat. No. 5,420,286) giving ≦50% of each enantiomer.

[0010] However, it should be noted that all tobacco products contain the(S)-nicotine enantiomer only. Therefore, it is desirable to useenantiomerically pure (S)-nicotine derivatives in the differentprophylactic and therapeutic applications.

DESCRIPTION OF THE INVENTION

[0011] The present invention provides a new method of producingenantiomerically pure 6-substituted (S)-nicotine derivatives in goodyields and high enantiomeric purity and new intermediate compounds foruse in said method.

[0012] More specifically, the present invention is directed to a methodof producing a 6-substituted (S)-nicotine derivative with the generalformula (III),

[0013] wherein R is an optionally substituted alkyl, alkenyl, alkynyl,amido or amino group.

[0014] The method comprises the steps of

[0015] a) reacting (S)-nicotine-N1-oxide with an organic nitrogen baseA, selected from trialkylamine, dialkylbenzylamine,dialkylcyclohexylamine and pyridine in which the alkyl groups may beindividually selected from lower alkyl groups, and an electrophiliccompound, if appropriate in the presence of a organic solvent to producea (S)-nicotine derivative with the general formula

[0016] wherein

[0017] A represents a cationic radical of the organic nitrogen base, and

[0018] Y represents an anion formed by the electrophilic compound,

[0019] b) reacting the compound (I) with a nucleophilic reagent toproduce the (S)-nicotine derivative with the general formula

[0020] wherein Nu represents the nucleophile, and reacting the compound(II) with an optionally substituted alkyn to produce a 6-substituted(S)-nicotine derivative with the formula (III) wherein R is anoptionally substituted alkyn group, followed by the optional steps ofhydrogenation of the triple bond of the alkyne to produce a compoundwith the formula (III) wherein R is an alkyl or alkenyl group orreacting the compound (II) with an amide anion to produce(S)-6-aminonicotine which then is coupled with an optionally substitutedcarboxylic acid to produce a 6-substituted (S)-nicotine derivative withthe formula (III) wherein R is an optionally substituted amido groupfollowed by the optional step of reduction of the amide to produce acompound with the formula (III) wherein R is an amino group.

[0021] In a preferred embodiment the produced compounds are thosewherein the substituent R is

[0022] —X—Y—Z-Q

[0023] wherein

[0024] X is —NH—CO— or —NH— or —C≡C— or —C≡C— or —CH₂—;

[0025] Y is —(CH₂)_(k)— or (CH₂)_(m)—C₆H₁₀(CH₂)_(n)— or(CH₂)_(m)—C₆H₄—(CH₂)_(n)—

[0026] wherein k=0-20, m=0-6, and n=0-6, when

[0027] Z is —NH— and Q is H

[0028] and

[0029] X is —NH—CO— or —C≡C— or —C═C— or —CH₂—,

[0030] Y is —(CH₂)_(m)—C₆H₁₀—(CH₂)_(n)— or (CH₂)_(m)—C₆H₄(CH₂)_(n)—

[0031] wherein m=0-6, and n=0-6, when

[0032] Z is —CO— and Q is —OH

[0033] and

[0034] X is —C≡C— or —C═C—,

[0035] Z is —CO— and Q is —OH, when

[0036] Y is —(CH₂)_(k)—

[0037] wherein k=0-20.

[0038] These compounds are, in racemic form, comprised by our earlierinternational patent application WO 9961054.

[0039] In another preferred embodiment A represents an organic nitrogenbase selected from the group consisting of: trialkylamine,dialkylbenzylamine, dialkylcyclohexylamine and pyridine in which thealkyl groups may be individually selected from lower alkyl groups, and Yrepresents an arylsulphonate ion, a chloride ion or a loweralkylcarboxylate ion.

[0040] In a most preferred embodiment A represents trimethylamine,triethylamine, tripropylamine, tributylamine, N,N-dimethylbenzylamine,N,N-diethylbenzylamine, N,N-dimethylcyclohexylamine andN,N-diethylcyclohexylamine, and Y represents a benzenesulphonate ion, achloride ion or an acetate ion.

[0041] In yet another embodiment of the method off the invention thenucleophilic reagent is selected from the group consisting ofhalogenating agents.

[0042] The present invention is also directed to the intermediatecompound of the formula

[0043] in which

[0044] A represents the cationic radical of an organic nitrogen base

[0045] Y represents an anion formed by an electrophilic compound.

[0046] Also in this aspect of the invention A preferably represents anorganic nitrogen base selected from the group consisting of:trialkylamine, dialkylbenzylamine, dialkylcyclohexylamine and pyridine,in which the alkyl groups may be individually selected from lower alkylgroups, and Y represents an arylsulphonate ion, a chloride ion or alower alkylcarboxylate ion. Most preferably A represents trimethylamine,triethylamine, tripropylamine, tributylamine, N,N-dimethylbenzylamine,N,N-diethylbenzylamine, N,N-dimethylcyclohexylamine andN,N-diethylcyclohexylamine, and Y represents a benzenesulphonate ion, achloride ion or an acetate ion.

[0047] The 6-substituted (S)-nicotine derivatives produced by the methodof the invention may be coupled to carrier proteins in the same way asdisclosed in our international patent application WO 9961054. Examplesof suitable carrier proteins are keyhole limpet hemocyanin (KLH),tetanus toxoid, diphtheria toxoid, non-toxic mutant diphtheria toxoidCRM₁₉₇, outer membrane protein complex (OMPC) from Neisseriameningitidis, the B subunit of heat-labile Escherichia coli, andrecombinant exoprotein A from Pseudomonas aeruginosa (rEPA).

[0048] The 6-substituted (S)-nicotine derivatives produced by the methodof the invention coupled to carrier proteins will find use asvaccines/immunogens for prophylactic and/or therapeutic immunologicaltreatment of nicotine dependence from tobacco products to achieve harmreduction in an individual.

[0049] The present invention will now be further illustrated byreference to the following description of synthesis of typical examplesof intermediate compounds and end products. However, these illustratedembodiments are not to be considered as limitations to the scope of theinvention defined in the claims.

[0050] Description of Synthesis of Compounds

[0051] The starting material for the synthesis, (S)-nicotinemono-N1-oxide, is obtained from (S)-nicotine as previously described inthe literature, and all the other chemicals used in the illustratedsyntheses are either bought or synthesized as previously described inour international patent application WO 9961054.

[0052] In the following Scheme 1 the synthetic pathway for producing thecompounds of the structural formulae (I)-(III) is illustrated withexemplary compounds. The 6-substituted (S)-nicotine compounds 5-10 aredisclosed, as racemates, in our international patent application WO9961054.

[0053] (S)-Trimethyl-[5-(1-methyl-pyrrolidin-2-yl)-pyridin-2-yl]ammoniumBenzenesulfonate (1).

[0054] Trimethylamine (5.9 g, 0.1 mol) was condensed at −25° C. into astirred solution of (S)-nicotine mono-N1-oxide¹ (1.77 g, 0.01 mol) indry CH₂Cl₂ (20 mL). A solution of benzenesulfonyl chloride (3.7 g, 0.02mol) in dry CH₂Cl₂ (15 mL) was added dropwise at −15° C., over a periodof 60 min. The mixture was stirred at this temperature for 60 min andthen allowed to reach room temperature. After 3 h at room temperature,the reaction mixture was concentrated in vacuo. The residue was treatedwith CH₂Cl₂ (50 mL) and most of the trimethylamine hydrochloride wasfiltered off and the solution was concentrated in vacuo. The residue waspurified by flash chromatography [Al₂O₃, CHCl₃, then CHCl₃/MeOH,(15:1)], to yield 2.86 g (76%) of product. An analytical sample wasobtained by crystallization from MeOH/benzene.

[0055] Anal. Calcd. for C₁₉H₂₇N₃SO₃.0.25H₂O: C, 59.7; H, 7.3; N, 11.0.Found: C, 59.7; H, 7.2; N, 10.9; mp (MeOH/benzene): 149.0-151.0° C.(dec); [α]_(D) ^(rt) −60.0° [c 0.9, MeOH]

[0056]¹H NMR (270 MHz, CDCl₃): δ 8.46 (br s, 1H); 8.25 (d, J=8.5 Hz,1H); 7.88 (m, 3H); 7.33 (m, 3H); 3.84 (s, 9H); 3.27 (br t, J=7.5 Hz,2H); 2.40 (dd, J=17.5, 8.5 Hz, 1H); 2.24(m, 4H); 1.89 (m, 2H); 1.66 (m,1H). ¹³C NMR (68 MHz, CDCl₃): δ 156.2, 148.2, 146.7, 140.7, 2×129.6,2×128.3, 126.1, 115.4, 67.9, 56.9, 3×55.5, 40.2, 35.1, 22.8, 1.2.

[0057] (S)-6-Chloronicotine (2)².

[0058] A solution of 1 (130 mg, 0.3 mmol) in dry 1,2-dichloroethane (10mL) was saturated with HCl (g), and the reaction mixture was stirred at35° C. for 22 h. The solvent was evaporated in vacuo. The residue wasdissolved in CH₂Cl₂ and the pH of the mixture was brought to pH˜7-8 byaddition of saturated aq NaHCO₃. The organic layer was washed withbrine, dried (MgSO₄), filtered and concentrated in vacuo to yield abrownish oil. The oil was chromatographed [Al₂O₃, iso-hexane/AcOEt,(4:1)] to afford 53.3 mg (78%) of 2 as a pink oil. [α]_(D) ²³ −154.3° (c1.0 MeCN) [lit.² [α]_(D) ²³ −154° (c 1.0 MeCN)].

[0059] (S)-6-Bromonicotine (3).

[0060] A solution of 1 (1.1 g, 2.9 mmol) in dry CH₂Cl₂ (50 mL) wassaturated with HBr [(g) dried with Mg(ClO₄)₂], and the reaction mixturewas stirred at ambient temperature for 30 h. The solvent was evaporatedin vacuo. The residue was dissolved in CH₂Cl₂ and the pH of the mixturewas brought to pH˜7-8 by addition of saturated aq NaHCO₃. The organiclayer was washed with brine, dried (MgSO₄), filtered and concentrated invacuo to yield a brownish oil. The residue was chromatographed [Al₂O₃,iso-hexane/AcOEt (4:1)] to afford 0.53 g (75%) of 3 as a colorless oil(turns reddish with time).

[0061] 3: ¹H NMR (270 MHz, CDCl3): δ 8.27 (d, 1H; J=2.5 Hz); 7.57 (dd,1H; J=8.3, 2.5 Hz); 7.42 (dd, 1H; J 8.6, 0.3 Hz); 3.21 (ddd, 1H; J=8.6,8.6, 2.2 Hz); 3.06 (brt, 1H; J=8.3 Hz); 2.30 (dd, 1H; J=17.6, 9.2 Hz);1.88 (m, 2H); 2.18 (m, 4H); 1.66 (m, 1H). ¹³C NMR (68 MHz, CDCl₃): δ149.6, 140.5, 138.4, 137.8, 128.0, 67.9, 56.8, 40.2, 35.2, 22.6.

[0062] MS (EI, 70 eV) m/z 240; 242 (1:1) (M⁺); [α]_(D) ^(rt) −132.5° (c1, CH₃CN); The enantiomeric purity was determined by chiral HPLC.

[0063] Treatment of 3 with picric acid in EtOH:H₂O yielded themonopicrate salt 3 monopicrate: mp (EtOH/H₂O) 141.0-143.0° C.

[0064] Anal. Calcd. for C₁₆H₁₆N₅O₇Br: C, 40.9; H, 3.4; N, 14.9. Found:C, 40.4; H, 3.4; N, 14.7.

[0065] 3 monopicrate salt: ¹H NMR (270 MHz, CD₃COCD₃): δ 8.75 (s, 2H);8.61 (d, 1H; J=2.6 Hz); 8.15 (dd, 1H, J=8.4, 2.6 Hz); 7.64 (d, 1H; J=8.4Hz); 4.68 (brs, 1H); 4.08 (br s, 1H); 3.57 (m, 1H); 3.03 (s, 3H); 2.54(m, 4H). ¹³C NMR (68 MHz, CD₃COCD₃): δ 162.5, 152.3, 144.3, 142.9,2×140.3, 129.5, 128.4, 2×126.5, 70.8, 57.6, 39.8, 31.7, 22.4.

[0066] (S)-6-Aminonicotine (4)³.

[0067] Potassium metal (78 mg, 2 mmol) was added to ˜15 mL of NH₃followed by 5-10 mg of Fe NO₃)₃ 9H₂O to catalyze amide formation. Afterthe potassium amide had formed (gray suspension), a solution of 3 (120mg, 0.5 mmol) in dry ether (5 mL) was added. The mixture was stirred for20 min and quenched with excess of solid NH₄Cl. Ammonia was evaporatedand the solid residue was treated with saturated aq. K₂CO₃ and extractedwith ether (5×5 mL). The combined ether extracts was dried with KOH andthen evaporated. The residue was purified by column chromatography[silica, CHCl₃/MeOH saturated with ammonia, (20:1)] to give 54 mg (61%)of 4: mp 66-67° C.; [α]_(D) ^(rt)=−120.1 (c 1, MeOH).

[0068] 4: ¹H NMR (270 MHz, CDCl₃): δ 7.95 (d, 1H; J=2.0 Hz); 7.5 (dd,1H; J=8.4; 2.3 Hz); 6.51 (d, 1H; J 8.4 Hz); 4.44 (brs, 2H); 3.22 (ddd,1H; J=9.6, 9.6, 2.0 Hz); 2.94 (brt, 1H; J=8.3 Hz); 2.25 (dd, 1H; J=17.5,9.1 Hz); 2.09 (m, 4H); 1.94 (m, 1H); 1.76 (m, 2H).

[0069]¹³C NMR (68 MHz, CDCl₃) δ 158.1, 147.4, 137.2, 128.2, 109.1, 68.7,57.0, 40.3, 34.7, 22.4.

[0070] MS (EI, 70 eV) m/z 177 (M+). The enantiomeric purity wasdetermined by chiral HPLC.

[0071](S)-trans-4-[3-(5-(1-Methyl-2-pyrrolidinyl)-2-pyridinyl)prop-2-ynyl]cyclohexanecarboxylicAcid Methyl Ester (5).

[0072] A mixture of 3 (0.2 g, 0.8 mmol),bis(triphenylphosphine)palladium dichloride (0.014 g, 0.02 mmol) and CuI(0.004 g, 0.02 mmol) in 5 mL of Et₃N was deoxygenated with N₂.trans-4-Prop-2-ynylcyclohexancarboxylic acid methyl ester⁴ (0.2 g, 1.1mmol) was added and the reaction mixture was heated at 120° C. for 45min in a sealed vessel. The Et₃N was evaporated in vacuo and the residuewas dissolved in EtOAc, washed with saturated aqueous NaHCO₃ andextracted with 2×15 mL of 2N HCl. The acidic aqueous phase was extractedwith EtOAc (3×20 mL). The aqueous layer was saturated with solid NaHCO₃and extracted with EtOAc (3×20 mL). The organic phase was washed withbrine, dried (Na₂SO₄), filtered and concentrated in vacuo. The residuewas chromatographed [silica, acetone/iso-hexane (1:2)] to yield 0.26 g(93%) of 5.

[0073] IR (film) ν_(max) 2226 cm⁻¹. ¹H NMR (CDCl₃, 270 MHz) δ 8.40 (brs, 1H), 7.63 (dd, J=8.1; 2.0 Hz, 1H), 7.30 (d, J=8.1 Hz, 1H), 3.60 (s,3H), 3.25-3.18 (m, 1H), 3.08 (app t, 1H), 2.31-2.08 (m, 5H), 2.12 (s,3H), 1.98-1.32 (m, 10H), 1.15-0.99 (m, 2H); ¹³C NMR (CDCl₃, 68 MHz) δ176.4, 149.6, 142.8, 137.2, 135.1, 126.9, 89.0, 81.6, 68.8, 56.9, 51.6,43.0, 40.2, 36.5, 35.0, 31.7, 28.8, 26.8, 22.6. MS (EI, 70 eV) m/z 340(M⁺) Anal. Calcd. for C₂₁H₂₈N₂O₂: C, 74.09; H, 8.29; N, 8.23%. Found: C,73.84; H, 8.27; N, 8.32%.

[0074] [α]_(D) ^(rt)=−84.0 (c 1, MeOH)

[0075](S)-trans-4-[3-(5-(1-Methyl-2-pyrrolidinyl)-2-pyridinyl)propyl]cyclohexanecarboxylicAcid Methyl Ester (6).

[0076] A solution of 5 (0.13 g, 0.4 mmol) in MeOH (40 mL) washydrogenated at room temperature and atmospheric pressure over 10% Pd/C(0.06 g). After 40 min the catalyst was filtered off and washed withMeOH. The volatiles was evaporated under reduced pressure and theresidue was chromatographed [SiO₂, acetone/iso-hexane (1:2)] to afford0.13 g (93%) of 6.

[0077]¹H NMR (CDCl₃, 270 MHz) δ 8.39 (d, J=2.0 Hz, 1H), 7.67 (dd, J=7.9;1.8 Hz, 1H), 7.10 (d, J=7.9 Hz, 1H), 3.62 (s, 3H), 3.31-3.25 (m, 1H),3.12 (app t, 1H), 2.72 (t, J=7.7 Hz, 2H), 2.39-2.12 (m, 2H), 2.18 (s,3H), 2.02-1.65 (m, 9H), 1.44-1.29 (m, 2H), 1.30-1.22 (m, 3H), 0.96-0.80(m, 2H); ¹³C NMR (CDCl₃, 68 MHz) δ 176.8, 161.8, 149.1, 135.5, 134.6,122.9, 69.0, 57.0, 51.6, 43.6, 40.2, 38.5, 37.1, 37.0, 34.8, 32.4, 29.1,27.4, 22.5. MS (EI, 70 eV) m/z 344 (M⁺) Anal. Calcd. forC₂₁H₃₂N₂O₂x0.2H₂O: C, 72.46; H, 9.37; N, 8.05%. Found: C, 72.34; H,9.44; N, 8.06%; [α]_(D) ^(rt)=−61.0 (c 1, MeOH).

[0078](S)-trans-4-[3-(5-(1-Methyl-2-pyrrolidinyl)-2-pyridinyl)propyl]cyclohexanecarboxylicAcid (7).

[0079] A mixture of 6 (0.11 g, 0.3 mmol) and KOH (0.025 g, 0.45 mmol) in50% aqueous MeOH (10 mL) was heated under reflux for 30 min. Thereaction mixture was acidified with HOAc to pH 8 and the solvents wereevaporated in vacuo. The crude product was purified by columnchromatography (silica gel, CHCl₃/MeOH, gradient of MeOH 10% to 50%) toafford 0.077 g (74%) of 7.

[0080]¹H NMR (CD₃OD, 270 MHz) δ 8.44 (br s, 1H), 7.83 (dd, J=8.1; 2.2Hz, 1H), 7.34 (d, J=8.1 Hz, 1H), 3.50 (app t, 1H), 3.43-3.35 (m, 1H),2.77 (t, 7.7 Hz, 2H), 2.66-2.56 (m, 1H), 2.40-2.26 (m, 1H), 2.31 (s,3H), 2.11-1.67 (m, 10H), 1.45-1.23 (m, 5H), 0.98-0.86 (m, 2H); ¹³C NMR(CDCl₃, 68 MHz) δ 184.0, 163.5, 149.6, 138.1, 134.6, 124.8, 70.3, 57.7,40.2, 38.8, 38.5, 38.2, 34.7, 33.9, 31.0, 28.6, 23.2; [α]_(D)^(rt)=−49.0 (c 2, MeOH).

[0081](S)-2-(3-Hydroxy-3-methylbut-1-ynyl)-5-(1-methyl-2-pyrrolidinyl)pyridine(8).

[0082] A mixture of 3 (0.2 g, 0.8 mmol), triphenylphosphine (0.022 g,0.08 mmol), 10% Pd/C (0.022 g, 0.021 mmol in Pd), CuI (0.016 g, 0.08mmol) and K₂CO₃ (0.24 g, 2.0 mmol) in 30 mL of a mixture DME/H₂O (1:1)was deoxygenated with N₂. The mixture was stirred at room temperaturefor 30 min and then 2-methyl-3-butyn-2-ol (0.17 g, 2.0 mmol) was added.After stirring under reflux for 7 h the mixture was filtered over acelite pad and concentrated in vacuo to half the volume. The residue wasmade acidic with 2M HCl and then washed with toluene (2×10 mL). Theaqueous phase was saturated with K₂CO₃ and extracted with EtOAc (3×20mL), washed with brine, dried over Na₂SO₄ and concentrated in vacuo. Theresidue was purified by column chromatography [silica gel,iso-hexane/acetone (1:1)] to give 0.131 g (66%) of 8.

[0083] IR (film) ν_(max) 2238 cm⁻¹. ¹H NMR (CDCl₃, 270 MHz) δ 8.43 (brs, 1H), 7.65 (dd, J=8.0; 2.1 Hz, 1H), 7.33 (d, J=8.1 Hz, 1H), 4.05 (brs, 1H), 3.23-3.16 (m, 1H), 3.05 (app t, 1H), 2.31-2.21 (m, 1H),2.18-2.07 (m, 1H), 2.11 (s, 3H), 1.94-1.60 (m, 3H), 1.64 (s, 6H); ¹³CNMR (CDCl₃, 68 MHz) δ 149.6, 141.9, 138.2, 135.4, 127.2, 94.5, 81.2,68.8, 65.0, 57.1, 40.5, 35.2, 31.4, 22.6. MS (EI, 70 eV) m/z 244 (M⁺)Anal. Calcd. for C₁₅H₂₀N₂O: C, 73.74; H, 8.25; N, 11.46%. Found: C,73.56; H, 8.36; N, 11.40%; [α]_(D) ^(rt)=−172.0 (c 1, MeOH).

[0084] (S)-2-Ethynyl-5-(1-methyl-2-pyrrolidinyl)pyridine (9).

[0085] Compound 8 (0.12 g, 0.5 mmol) and NaH as a 60% dispersion inmineral oil (0.005 g, 0.13 mmol) were dissolved in dry toluene (10 mL).The stirred solution was slowly distilled until the boiling point of thedistillate reached 110° C. The rest of the toluene was evaporated invacuo. The residue was chromatographed [SiO₂, CHCl₃/MeOH, (10:1)] togive 0.062 g, (67%) of 9 as a yellow oil.

[0086]¹H NMR (CDCl₃, 270 MHz) δ 8.49 (d, J=2.2 Hz, 1H), 7.67 (dd, J=8.0;2.1 Hz, 1H), 7.43 (d, J=7.9 Hz, 1H), 3.25-3.18 (m, 1H), 3.11-3.03 (m,2H), 2.34-2.24 (m, 1H), 2.23-2.09 (m, 1H), 2.14 (s, 3H), 1.98-1.60 (m,3H); ¹³C NMR (CDCl₃, 68 MHz) δ 149.9, 141.2, 139.2, 135.2, 127.5, 83.0,76.9, 68.8, 57.1, 40.5, 35.4, 22.8. MS (EI, 70 eV) m/z 186 (M⁺) Anal.Calcd. for C₁₂H₁₄N₂: C, 77.39; H, 7.58; N, 15.04%. Found: C, 77.29; H,7.44; N, 14.89%; [α]_(D) ^(rt)=−148.5 (c 1, MeOH).

[0087] (S)5-(1-Methyl-2-pyrrolidinyl)-2-pyridinylpropiolic Acid (10).

[0088] A solution of 9 (0.053 g, 0.3 mmol) in THF (8 mL) was cooled to−78° C. and BuLi (1.6M solution in hexane, 0.2 mL, 0.32 mmol) was added.The reaction mixture was stirred for 0.5 h at −78° C. and then CO₂ gaswas added. After an additional 1 h at −78° C. the reaction mixture wasallowed to warm to room temperature. THF was evaporated in vacuo and theresidue was purified by column chromatography [silica gel, CHCl₃/MeOH,(1:1)]; yield 0.04 g, (87% based on recovered 9) of 10.

[0089]¹H NMR (CD₃OD, 270 MHz) δ 8.48 (d, J=1.8 Hz, 1H), 7.84 (dd, J=8.1;2.2 Hz, 1H), 7.59 (d, J=8.1 Hz, 1H), 3.28-3.20 (m, 2H), 2.44-2.39 (m,1H), 2.31-2.21 (m, 1H), 2.18 (s, 3H), 2.01-1.68 (m, 3H); ¹³C NMR (CD₃OD,68 MHz) δ 160.6, 150.6, 142.4, 140.3, 137.6, 129.2, 87.2, 78.3, 70.0,58.0, 40.8, 35.9, 23.5; [α]_(D) ^(rt)=−42.0 (c 0.5, MeOH).

1. A method of producing a 6-substituted (S)-nicotine derivative withthe general formula (III),

wherein R is an optionally substituted alkyl, alkenyl, alkynyl, amido oramino group, optionally coupled to a carrier protein, comprising thesteps of a) reacting (S)-nicotine-N1-oxide with an organic nitrogen baseA, selected from trialkylamine, dialkylbenzylamine,dialkylcyclohexylamine and pyridine in which the alkyl groups may beindividually selected from lower alkyl groups, and an electrophiliccompound, if appropriate in the presence of an organic solvent toproduce a (S)-nicotine derivative with the general formula

wherein A represents a cationic radical of the organic nitrogen base,and Y represents an anion formed by the electrophilic compound, b)reacting the compound (I) with a nucleophilic reagent to produce the(S)-nicotine derivative with the general formula

wherein Nu represents the nucleophile, and reacting the compound (II)with an optionally substituted alkyn to produce a 6-substituted(S)-nicotine derivative with the formula (III) wherein R is anoptionally substituted alkyn group, followed by the optional steps ofhydrogenation of the triple bond of the alkyne to produce a compoundwith the formula (III) wherein R is an alkyl or alkenyl group orreacting the compound (II) with an amide anion to produce(S)-6-aminonicotine which then is coupled with an optionally substitutedcarboxylic acid to produce a 6-substituted (S)-nicotine derivative withthe formula (III) wherein R is an optionally substituted amido groupfollowed by the optional step of reduction of the amide to produce acompound with the formula (III) wherein R is an amino group, whereuponthe compound (III) is optionally coupled via the terminal carboxylicacid or amine group to a carrier protein.
 2. A method according to claim1, wherein the substituent R is —X—Y—Z-Q wherein X is —NH—CO— or —NH— or—C≡C— or —C═C— or —CH₂—; Y is —(CH₂)_(k)— or —(CH₂)_(m)—C₆H₁₀—(CH₂)_(n)—or —(CH₂)_(m)—C₆H₄—(CH₂)_(n)— wherein k=0-20, m=0-6, and n=0-6, when Zis —NH— and Q is H or a carrier protein, and X is —NH—CO— or —C≡C— or—C═C— or —CH₂—, Y is —(CH₂)_(m)—C₆H₁₀—(CH₂)_(n)— or—(CH₂)_(m)—C₆H₄—(CH₂)_(n)— wherein m=0-6, and n=0-6, when Z is —CO— andQ is —OH or a carrier protein, and X is —C≡C— or —C═C—, Z is —CO— and Qis —OH or a carrier protein, when Y is —(CH₂)_(k)— wherein k=0-20. 3.Method according to claim 1 or 2, wherein A represents an organicnitrogen base selected from the group consisting of: trialkylamine,dialkylbenzylamine, dialkylcyclohexylamine and pyridine in which thealkyl groups may be individually selected from lower alkyl groups, and Yrepresents an arylsulphonate ion, a chloride ion or a loweralkylcarboxylate ion.
 4. Method according to any one of claims 1-3,wherein A represents trimethylamine, triethylamine, tripropylamine,tributylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine,N,N-dimethylcyclohexylamine and N,N-diethylcyclohexylamine, and Yrepresents a benzenesulphonate ion, a chloride ion or an acetate ion. 5.Method according to any one of claims 1-4, wherein the nucleophilicreagent is selected from the group consisting of halogenating agents. 6.A compound of the formula

in which A represents the cationic radical of an organic nitrogen base Yrepresents an anion formed by an electrophilic compound.
 7. A compoundaccording to claim 1, wherein A represents an organic nitrogen baseselected from the group consisting of: trialkylamine,dialkylbenzylamine, dialkylcyclohexylamine and pyridine in which thealkyl groups may be individually selected from lower alkyl groups, and Yrepresents an arylsulphonate ion, a chloride ion or a loweralkylcarboxylate ion.
 8. A compound according to claim 1, wherein Arepresents trimethylamine, triethylamine, tripropylamine, tributylamine,N,N-dimethylbenzylamine, N,N-diethylbenzylamine,N,N-dimethylcyclohexylamine and N,N-diethylcyclohexylamine, and Yrepresents a benzenesulphonate ion, a chloride ion or an acetate ion.